I-4 2.5L 89 YJ refuses to start - runs rich if at all - JeepForum.com
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Unread 09-17-2013, 04:01 PM   #1
JeepArt
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1989 YJ Wrangler 
 
Join Date: Sep 2013
Location: Pottstown, PA
Posts: 51
I-4 2.5L 89 YJ refuses to start - runs rich if at all

Ok Jeepers, I'm looking for some advice.

Bought a 89 YJ I-4 2.5L and I've hit a snag. The jeep (when running) runs very rich. Black exhaust marks on the pavement where it's been idling, carbon fouling on the spark plugs and so on. Now to compound the issue, it refuses to start at all. Trying to start results in a gas odor from under the hood and no ignition.

Here's what I've done and tested:
  • Replaced distributor cap and rotor
  • Tested for spark (successful)
  • Replaced plugs
  • Replaced MAP sensor
  • Replaced O2 sensor
  • Replaced CPS
  • Cleaned Throttle Body Injector
  • Tested for fuel flow (successful)
  • Replaced fuel filter
  • Replaced air filter

Questions:
  • Any suggestions on other things to check to get her started?
  • What could cause her to run so rich when running?
  • I'm speculating the TBI could be a factor...what are the odds?
  • I haven't replaced the TPS yet but have one on order...should I do that as well?

Thanks in advance for your help getting this girl up and running.

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Unread 09-17-2013, 04:23 PM   #2
Siva283
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1995 YJ Wrangler 
 
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Location: Falling Waters, WV
Posts: 3,698
Quote:
Originally Posted by JeepArt View Post
Ok Jeepers, I'm looking for some advice.

Bought a 89 YJ I-4 2.5L and I've hit a snag. The jeep (when running) runs very rich. Black exhaust marks on the pavement where it's been idling, carbon fouling on the spark plugs and so on. Now to compound the issue, it refuses to start at all. Trying to start results in a gas odor from under the hood and no ignition.

Here's what I've done and tested:

[*]Replaced distributor cap and rotor[*]Tested for spark (successful)[*]Replaced plugs[*]Replaced MAP sensor[*]Replaced O2 sensor[*]Replaced CPS[*]Cleaned Throttle Body Injector[*]Tested for fuel flow (successful)[*]Replaced fuel filter[*]Replaced air filter


Questions:
[*]Any suggestions on other things to check to get her started?[*]What could cause her to run so rich when running?[*]I'm speculating the TBI could be a factor...what are the odds?[*]I haven't replaced the TPS yet but have one on order...should I do that as well?


Thanks in advance for your help getting this girl up and running.
Do a fuel pressure test. I am betting you have a bad pressure regulator. You should have I think its 14 psi with the tbi. Someone will need to verify that though.

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1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
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Unread 09-17-2013, 04:31 PM   #3
JeepArt
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Would low fuel pressure be symptomatic of running rich when running at all?
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Unread 09-17-2013, 05:25 PM   #4
Siva283
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Quote:
Originally Posted by JeepArt View Post
Would low fuel pressure be symptomatic of running rich when running at all?
No but high fuel pressure would.

Sent from my SPH-L300 using JeepForum
__________________
1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
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Unread 09-18-2013, 07:09 AM   #5
Que89YJ
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Posts: 15,707
The pressure is only 14 psi on the TBI. You should look at the rebuild kit with replacement injector for the throttlebody. This is in the Schaef thread below:

How to google the forum:
http://www.jeepforum.com/forum/f12/f...oogle-1003734/

To download the fsm:
http://dl.dropbox.com/u/40590346/87-88%20YJ%20Jeep%20Wrangler%20FSM%20manual.pdf
http://dl.dropbox.com/u/40590346/1990%20Jeep%20Factory%20Service%20Manual.pdf

If you download the FSM and you are not a member of dropbox, please PM Ninjakid and join under him. It gives him more space to store and it is a real generous thing to get the manual for free!
http://jeepspace.jeepforum.com/ninjakid

Also lots of good info in Shaef's threads about his TBI:
http://www.jeepforum.com/forum/f12/8...ocess-1293442/
http://www.jeepforum.com/forum/f12/2...-idle-1293410/


Get a multimeter. Some of the pre 91 tbi sensors require an adjustment to setup when replaced. Since you are dealing with PO that probably didn't know, chances are you need to do some adjustments with the basic tune up. Wide open throttle switch(WOT), the throttle position sensor(TPS), Idle Speed Adjustment Motor(ISA), and the fuel pressure on the throttle body.
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Unread 09-18-2013, 07:11 AM   #6
Que89YJ
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Sorry, ignore the injector thing for now. Read through the thread and it tells you about measuring the pressure. x1000 with Siva. Measure it!
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Unread 09-18-2013, 07:57 PM   #7
JeepArt
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Will do on the pressure check...if I can get the Jeep running. The problem I'm facing now is that the engine won't start. Fuel is being delivered, plenty of spark, but no ignition. Ideas? It's headed for the shop if I can't get this figured out. TIA
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Unread 09-18-2013, 08:08 PM   #8
Que89YJ
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No ignition.... Yes. Check power at the coil. Replace the coil ICM. Most good parts stores have a testor for it. You can check fuel pressure by jumping the fuel pump relay with a small wire between 30/87 in the relay socket.
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Unread 09-18-2013, 08:16 PM   #9
JeepArt
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What's odd is it was running, rough and rich mind you, but it was running. Maybe this helps... When it was running it ran Ok until I stopped the Jeep then it wouldn't restart, even with starter fluid.
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Unread 09-18-2013, 08:18 PM   #10
Xpress
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Check the fuel pressure before you do anything else.
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Unread 09-18-2013, 08:24 PM   #11
JeepArt
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I'm picking up a fuel pressure gauge tomorrow along with a new TPS which I was planning to install anyway. Another observation: after cleaning the TBI I fired the engine and saw what looked like a good amount of fuel come from the injector into the throttle body.
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Unread 09-18-2013, 08:28 PM   #12
95YJRusso
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Does the starter motor turn over?
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Unread 09-18-2013, 08:33 PM   #13
JeepArt
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Starter motor turns over. I get spark from the distributor. New plugs all checked and gap. Visually confirmed fuel into the throttle body and out of the injector.

I can't help but think it's electrical/computer related because of the hatchet job the previous owner did on the wiring to install a stereo (turn on the headlights and the radio loses power... Go figure.)
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Unread 09-18-2013, 09:20 PM   #14
Que89YJ
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Check the pressure. If you are getting spark then there is only fuel and timing. I miss understood what you said about spark. Siva is right.
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Unread 09-19-2013, 07:09 AM   #15
Siva283
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Location: Falling Waters, WV
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Quote:
Originally Posted by Que89YJ View Post
Check the pressure. If you are getting spark then there is only fuel and timing. I miss understood what you said about spark. Siva is right.
I remembered some of what you taught me.
__________________
1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
Siva283 is offline   Reply With Quote Quick reply to this message
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